The purpose of the study is to determine the predictive values and prognostic accuracies of CSF dynamic measures, the TAP -TEST (high-volume cerebrospinal fluid withdrawal), resistance to CSF outflow and compliance in the prediction of shunt-treatment outcome in patients with idiopathic normal pressure hydrocephalus.

Any gait disturbance of both legs that does not fulfill the criteria of typical INPH, but is compatible with INPH.

MMSE score < 21

Bladder instability and postural instability may be present.

Radiological criteria (MRI):

Symmetrical communicating quadri-ventricular enlargement without major parenchymal lesions. Single cortical infarcts and lacunar infarcts may be present.

Evans index > 0.30.

Moderate cortical atrophy and moderate to severe leuco-araiosis may be present.

Exclusion Criteria:

Secondary Normal pressure Hydrocephalus

Non-communicating hydrocephalus

Secondary NPH (after SAH, trauma, infection, neurosurgical procedure). Trauma or infection are regarded as relevant if the patient was unconscious in relation to the trauma or required hospitalisation for his meningo-encephalitis.

INPH-patients later shown to have ICP > 18 mm Hg.

Contra-indications to surgery.

Patients refusing shunt surgery

Restricted life-expectancy

Patients not capable of managing the tests or investigations at entry of the study

Contacts and Locations

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Please refer to this study by its ClinicalTrials.gov identifier: NCT00874198